1. Field of the Invention
The present invention relates to a detector, and particularly to a metal detector for detecting metal objects.
2. Description of the Related Art
Nowadays, metal detectors are used in various fields and are based on the measurement of changes in the electromagnetic field, which are brought about by metal objects located in a zone to be monitored. Metal detectors are used in the security inspections, such as checking passengers at airports, checking visitors in particularly highly protected buildings or installations. Metal detectors are also used for a wide range of purposes in industry.
Generally speaking, a conventional metal detector includes a transmitting coil, a receiving coil, an oscillator, a cymoscope, a processor, a transducer, and so on. The processor identifies and processes signals generated by the receiving coil, the oscillator, and the cymoscope, and then signals the transducer to output an audible sound according to the processing result. The conventional metal detector is very complicated and expensive, therefore it is not feasible for mass production and adopted widely throughout the various industries. Moreover, analogue signals such as current signals, are easily influenced by the environmental factors while transmitting, thus reducing the accuracy of the detecting results.
What is desired, therefore, is to provide a metal detector with simple structure, low cost, and high accuracy.